Computer will not power up

Heyas all, hopefully I can get a pointer or so here....

My desktop developed HD/system problems about 9 months ago, so I bought a laptop and really really did intend to tear the desktop down, but only got to it in the last few days. Along the way, I thought I'd pump some new life into it while I wait as see how Vista and DirectX10 work out....sooo

I started with an ASUS P4C800E-Deluxe and P4 3.06HT kept my optical drives, added a brand new big WD 500gig HD, a new HIS Vid Board (ATI x1950 ICE AGP), and a new Corsair 620x power supply. I figured I would be ok, since I built this machine from scratch 3years ago (my first and worked well).

Problem is now, while I get some power to the board (the on the MOBO LED lights up, and the ethernet port glows) nothing happens, nothing at all.

I rechecked connections 3x and even tried the old PS which also did not go. This unit would at least power up before I powered down for the last time. It remained plugged, though off, to a quality UPS.

Question is: Could this be a dead CMOS battery? I've checked every relevant connection I could find and everything checks out. I figure I'll try this, but thought I'd post it here.

Thanks for any of your thoughts...

Tom

 

Usually, even if the CMOS battery is dead, the PC will still post with an error message stating that the CMOS battery is low/dead. Chances are your motherboard is dead You could try unplugging ALL devices (HD, optical drives, sound card, modem, video card if you have on board video also,etc). If you have a spare video card, try that. Extra RAM laying around? Try that. I've even seen faulty floppy drives cause a PC to not fire up. Just be sure that each time you remove/replace a device, that the power cord is removed from the PC. Many motherboards stay 'hot' when plugged in, even if they're shut down.

hopperdave2000

 

wow.....well thanks Dave...while not what I wanted to hear, it is helpful...will be a few days before I can try this approach..

Thanks for your thoughts on the matter.

Tom

 

I won't be able to really get into this for a few days. Should I unplug both power and communication connections to my drives (two optical, one HD), guess I could just do both, but trying to learn here...again, thanks for any assistance!

Tom

 

You could just unplug the data cable and leave the drive drawing power. If you do that, the system BIOS won't see the device you've unplugged, which may be OK. If you do it the other way around (disconnect the power but not the data cable), the BIOS will see the device, try to get a response from it, then complain when it doesn't, thus distorting the results of your test.

But unplugging just the data cable may defeat the purpose of the test. It's not impossible for a drive to fail in such a way that its logic circuitry is still OK, but it draws too much power because of an internal short. This may force the PSU to shut down to protect itself. Result: an apparently-dead system.

Best to disconnect both data and power cables. Then reconnect each drive one at a time (both cables), until the system fails to start. The last device connected is your prime suspect for replacement. (Don't forget to power down for each reconnection. Hot-plugging most equipment is definitely not a good idea. USB peripherals are an exception to the rule, and even then you may have to tell the OS to stop the device you're about to disconnect.)

 

I'd go for a failed PSU. Just because it it supplying some of the voltages doesn't mean all are working. You can buy power supply testers fairly cheaply wwhich tell you whether any of the required voltage outputs have failed. I use this